Introduction: Physical activity (PA) is associated with neuroprotective effects and a reduced risk of cognitive decline. However, evidence across diverse global populations remains limited. We examined the association between harmonized PA categories and cognitive impairment across seven large aging cohorts from Brazil, China, South Africa, Colombia, Europe, the United States, and India.

Methods: We conducted a pooled cross-cohort analysis including 227,392 participants from seven aging cohorts in Brazil (ELSI), China (CHARLS), South Africa (HAALSI), Colombia (SABE), Europe (SHARE), the United States (HRS), and India (LASI). Physical activity (PA) was harmonized into four categories (sedentary, insufficiently active, moderately active, and highly active) based on WHO 2020 guidelines. Cognitive impairment was defined as a cohort-specific global cognitive z-score < −1.5 SD). Multivariable logistic regression models estimated associations between PA categories and cognitive impairment, adjusting for age, sex, and cohort.

Results: Among 135,625 participants with complete data, all physical activity categories were associated with lower odds of cognitive impairment compared with sedentary individuals. Older age was independently associated with increased odds of impairment.

Conclusion: Across 18 countries, any level of PA was associated with lower odds of cognitive impairment. These findings highlight physical activity as a key modifiable determinant of cognitive health and support public health strategies to reduce sedentary behavior and promote regular activity.